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Highlights: Occupational exposure to particles during industrial packing was assessed. No significant increases were found during packing of a granulate fertilizer. One and two box models predicted adequately actual worker exposure. Including outdoor concentrations in models was seen to improve their performance. Models parametrization was seen to be a key issue to adequately predict exposure.

The interactions of emerging contaminants with the xenobiotic and endogenous metabolizing system of deep-sea fish were compared. The drugs diclofenac, fluoxetine, and gemfibrozil belong to different pharmaceutical classes with diverse mechanistic actions, and the personal care products triclosan, galaxolide, and nonylphenol are representative of antibacterial agents, nitro-musks, and surfactants, respectively. The fish compared are representative of the middle and lower slope of deep-sea habitats. The species were adults of Trachyrynchus scabrus, Mora moro, Cataetix laticeps, and Alepocehalus rostratus. The hepatic metabolic system studied were the activities associated with several cytochrome P450 isoforms (CYPs): 7-ethoxyresorufin-O-deethylase (EROD), benzyloxy-4-[trifluoromethyl]-coumarin-O-debenzyloxylase (BFCOD), and 7-ethoxycoumarin-O-deethylase (ECOD). Results showed differences in baseline activities and sensitivity to chemicals which were species, chemical, and pathway dependent. T. scabrous was the most sensitive species to chemical interactions with the xenobiotic and endogenous metabolizing (EROD and BFCOD) systems, especially in the case of diclofenac interference with BFCOD activity (IC50 = 15.7 ± 2.2 μM). Moreover, T. scabrous and A. rostratus possessed high basal ECOD activity, and this was greatly affected by in vitro exposure to diclofenac in T. scabrous also (IC50 = 6.86 ± 1.4 μM). These results highlight the sensitivity of marine fish to emerging contaminants and propose T. scabrous (middle slope) and A. rostratus (lower slope) as sentinels and the inclusion of ECOD activity as a sensitive biomarker to these exposures.

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Packing of raw materials in work environments is a known source of potential health impacts (respiratory, cardiovascular) due to exposure to airborne particles. This activity was selected to test different exposure and risk assessment tools, aiming to understand the effectiveness of source enclosure as a strategy to mitigate particle release. Worker exposure to particle mass and number concentrations was monitored during packing of 7 ceramic materials in 3 packing lines in different settings, with low (L), medium (M) and high (H) degrees of source enclosure. Results showed that packing lines L and M significantly increased exposure concentrations (119-609 µg m -3 respirable, 1150-4705 µg m -3 inhalable, 24755-51645 cm -3 particle number), while nonsignificant increases were detected in line H. These results evidence the effectiveness of source enclosure as a mitigation strategy, in the case of packing of ceramic materials. Total deposited particle surface area during packing ranged between 5.4-11.8x10 5 µm 2 min -1 , with particles depositing mainly in the alveoli (51-64%) followed by head airways (27-41%) and trachea bronchi (7-10%). The comparison between the results from different risk assessment tools (Stoffenmanager, ART, NanoSafer) and the actual measured exposure concentrations evidenced that all of the tools overestimated exposure concentrations, by factors of 1.5-8. Further research is necessary to bridge the current gap between measured and modelled health risk assessments.

Exposure to ceramic powders, which is frequent during handling operations, is known to cause adverse health effects. Finding proxy parameters to quantify exposure is useful for efficient and timely exposure assessments. Worker exposure during handling of five materials (a silica sand (S1), three quartzes (Q1, Q2 and Q3) and a kaolin (K1)) with different particle shape (prismatic and platy) and sizes (3.4 -120 µm) was assessed. Materials handling was simulated using a dry pendular mill under two different energy settings (low and high). Three repetitions of two kilos of material were carried out per material and energy conditions with a flow rate of 8 -11 kg/h. The performance of the dustiness index as a predictor of worker exposure was evaluated correlating material's dustiness indexes (with rotating drum and continuous drop) with exposure concentrations. Significant impacts on worker exposure in terms of inhalable and respirable mass fractions were detected for all materials. Mean inhalable mass concentrations during background were always lower than 40 µg/m 3 whereas during material handling under high energy settings mean concentrations were 187, 373, 243, 156 and 430 µg/m 3 for S1, Q1, Q2, Q3 and K1 respectively. Impacts were not significant with regard to particle number concentration: background particle number concentrations ranged between 10620 -46421 /cm 3 while during handling under high energy settings they were 20880 -40498 /cm 3 . Mean lung deposited surface area during background ranged between 27 -101 μm 2 /cm 3 whereas it ranged between 22 -42 μm 2 /cm 3 during materials handling. TEM images evidenced the presence of nanoparticles (≤ 100 nm) in the form of aggregates (300 nm -1 µm) in the worker area, and a slight reduction on mean particle size during handling was detected. Dustiness and exposure concentrations showed a high degree of correlation (R 2 = 0.77 -0.97) for the materials and operating conditions assessed, suggesting that dustiness could be considered a relevant predictor for workplace exposure. Nevertheless, the relationship between dustiness and exposure is complex and should be assessed for each process, taking into account not only material behaviour but also energy settings and workplace characteristics.

Mass balance models have proved to be effective tools for exposure prediction in occupational settings. However, they are still not extensively tested in real-world scenarios, or for particle number concentrations. An industrial scenario characterized by high emissions of unintentionally-generated nanoparticles (NP) was selected to assess the performance of a one-box model. Worker exposure to NPs due to thermal spraying was monitored, and two methods were used to calculate emission rates: the convolution theorem, and the cyclic steady state equation. Monitored concentrations ranged between 4.2 × 104–2.5 × 105 cm−3. Estimated emission rates were comparable with both methods: 1.4 × 1011–1.2 × 1013 min−1 (convolution) and 1.3 × 1012–1.4 × 1013 min−1 (cyclic steady state). Modeled concentrations were 1.4-6 × 104 cm−3 (convolution) and 1.7–7.1 × 104 cm−3 (cyclic steady state). Results indicated a clear underestimation of measured particle concentrations, with ratios modeled/measured between 0.2–0.7. While both model parametrizations provided similar results on average, using convolution emission rates improved performance on a case-by-case basis. Thus, using cyclic steady state emission rates would be advisable for preliminary risk assessment, while for more precise results, the convolution theorem would be a better option. Results show that one-box models may be useful tools for preliminary risk assessment in occupational settings when room air is well mixed.

Abstract. In aerosol science, there is an increasing interest to perform mobile measurements to obtain number size distribution of ultrafine particles (UFP), using portable instruments based on unipolar charging and size segregation by electrical particle mobility. Applications of such measurements range from ambient and indoor aerosol studies to source identification in work environments. However, knowledge on the actual measurement uncertainties of these portable instruments under various conditions has been limited. This investigation presents results from an intercomparison workshop conducted at the World Calibration Center for Aerosol Physics (WCCAP) in Leipzig, Germany, in January 2020. Manufacturers and users were invited to have their portable instruments tested and compared against reference instrumentation for particle number size distributions (PNSD) and total particle number concentration (PNC). In particular, the performances and uncertainties of the NanoScan SMPS (Scanning Mobility Particle Sizer) Model 3910 (TSI Inc.) and the Mini Wide Range Aerosol Spectrometer (WRAS) Model 1371 (Grimm Aerosol Technik) were investigated extensively against the WCCAP Mobility Particle Size Spectrometers (MPSS) and Condensation Particle Counters (CPC). A total of 11 TSI NanoScan SMPS and 4 GRIMM Mini WRAS instruments were characterized for ambient aerosols as well as lab-generated aerosols. The workshop results affirm that the portable instruments must be serviced and calibrated annually or prior field studies to provide measurements within the given uncertainties. It should be noted that users should carry out timely service, maintenance and calibration of portable instruments at their facilities. During initial inspection, non-serviced NanoScan SMPS instruments overestimated a dominant ultrafine aerosol mode by 120 % at around 80 nm. Maintenance and servicing improved the performance. Overall, the performance of NanoScan SMPS instruments improved for the ultrafine aerosol mode while the PNC in the fine aerosol mode still overestimated by up to 80 %. The latter effect seems to be systematically related to the unipolar charging of particles, and the reduced sensitivity of electrical particle mobility with increasing particle size above 200 nm. Due to shift in the second mode of bimodal distribution, particles are overcounted around 100 nm. With regard to the integral PNC, some of the NanoScan SMPS found to be in good agreement (i.e. within 20 %) compared to the reference CPC. In addition, a reasonably good unit-to-unit agreement within ±20 % was found for NanoScan SMPS instruments. The Mini WRAS instruments, after proper cleaning and servicing, provided improved results within ±15 % deviation in PNC in the ultrafine aerosol mode. Overall, most of the GRIMM Mini WRAS instruments (operating with software version 10.0) agrees well with PNC (i.e. 10–50 %) when the ultrafine mode was dominant. Conversely, PNC of the fine aerosol mode was systematically underestimated by 60 % above 100 nm. Except for one instrument, the integral PNC of the GRIMM Mini WRAS spectrometers were within an uncertainty range of ±20 % compared to the reference CPC. Additionally, it is important for users to note that the Mini WRAS performed significantly better when using software version 10.0 compared to version 8.2. The workshop results suggest that despite the above-mentioned uncertainties, these portable instruments are suited for mobile ultrafine particle measurements to detect relative differences in the PNSD such as source apportionment studies of ultrafine particles at work places or outdoors near sources.